bug#7041: comint seems to truncate from places other than the top

[Reuben Thomas via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

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On Tue, 8 Dec 2020 at 22:31, Lars Ingebrigtsen <larsi@gnus.org> wrote:

> Reuben Thomas <rrt@sc3d.org> writes:
>
> > If I try it now, it doesn't seem to truncate the buffer as expected: for
> example
> >
> > emacs -Q
> > M-: (add-to-list 'comint-output-filter-functions 'comint-truncate-buffer)
> > M-x term
> > C-c M-x set-variable comint-buffer-maximum-size 256 ; do this after M-x
> term
> > because before comint-buffer-maximum-size is not defined
> > $ seq 1 1024
> >
> > The entire output is retained, and not truncated. Truncation seems to
> happen at
> > 2048 lines. This does not even correspond to the original value of the
> variable
> > (1024).
>
> I'm not getting any truncation...  but that variable is about comint
> buffers, like in `M-x shell' and the like.  Is term-mode a comint
> buffer?  It's not derived from comint-mode, so I'm not sure whether this
> is supposed to work there?
>

Ah, that would seem to explain it! Indeed, `term-buffer-maximum-size`
defaults to 2048.

So this bug report is based on a misunderstanding, and you can close it,
sorry!

In investigating, I noticed that the following text in term.el appears to
be out of date:

;; Brief Command Documentation:
… for example:
;; M-s     comint-next-matching-input    Next input that matches ← This is
not true! It is bound to term-next-matching-input.

Is there any point retaining this documentation at the top of the file
where it doesn't appear in the manual or any docstring?

-- 
https://rrt.sc3d.org

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